The present invention relates to a wireless communication device that uses magnetic force in whole or part to attach itself to an article. Alteration of the magnetic force in whole or part detaches the wireless communication device from the article.
Wireless communication devices are attached to articles of manufacture to wirelessly communicate identification, tracking and other information concerning the article. Many of the wireless communication devices used to attach to an article are radio frequency devices. Such wireless communication device is attached to articles so that information may be received and communicated to and from the articles. These devices are attached to articles when information is needed, and the devices are detached when information is no longer needed concerning the original articles so that the devices may be reused on other articles of interest.
One common type of wireless communication device used for attachment to articles of manufacture is called a transponder tag. For example, many clothing retailers attach transponder tags to clothing for security purposes. The transponder tags are adapted to interact with a signal that is transmitted by a transmitter into a surveillance zone. If the transponder tag moves through the surveillance zone, a system identifies the unauthorized presence of the tagged article in the zone.
These transponder tags are typically attached by mechanical components. Authorized persons detach the transponder tag when the article is presented for purchase. To detach the tags, a external tool or device is used. Some tools involve use purely mechanical removal methods. Other tools contain magnetic devices that function to move internal mechanical components of the transponder tag that are keeping the tag attached to the article.
Thus, existing methods lack automation for attachment and detachment of wireless communication devices. For example, some transponders require a tool using mechanical methods and movements to detach the transponder from an article. Others require reception of a special signal before detachment is allowed of the communication device. Still others use an external tool for detaching that contains an electromagnet, but the electromagnet only aids in the movement of internal mechanical parts in the transponder tag. The electromagnet only aids in the detachment process and does not in and by itself detach the transponder tag from the article. Alteration of magnetic force for detachment of wireless communication devices is not used most likely, because the articles are usually not magnetic and thus, it is not possible to create a sufficient readily magnetic force between the wireless communication devices and the articles is not substantially possible.
The present invention relates to a wireless communication device for attachment to and detachment from articles having a magnetic magnetic surface portion so as to enable for wireless communication of tracking, identification and other information between the article and another location. In one embodiment, the magnetic surface portion is a conductive material. In another embodiment, the magnetic surface portion is a non-conductive material. The wireless communication device contains a magnet with magnetic attraction properties so that magnetic force can be used in whole or part to attach the wireless communication device to a magnetic surface portion of the article. To detach the wireless communication device from the article, the magnetic force is altered in the form of canceling, disabling or altering the force so that the wireless communication device no longer has sufficient attractive force to the magnetic surface portion to overcome the gravitational pull of the earth.
The wireless communication device contains an antenna, a control system, wireless communication electronics, and a magnet in its most basic form. The antenna receives and communicates signals to and from the wireless communication device. The wireless communication electronics is adapted to communicate and receive communication signals to and from the antenna. Receive communication signals are interpreted by the control system, and the control system sends out signals to be communicated by the wireless communication device to the wireless communication electronics. The magnet has a magnetic force that attaches to a magnetic surface portion of the article when the wireless communication device is in close proximity to the magnetic surface portion.
The magnet may be a natural magnet, electromagnet, or other type of material having magnetic properties that creates a magnetic force. An electromagnet may be comprised of a coil wound around a conductive core, such as metal or steel, whereby the control system provides a voltage across said coil from its power source to run a current through the magnetic surface portion, thereby creating an electromagnet. The wireless communication device may contain its own power source, such as a battery or reservoir capacitor, or may use communications received from an interrogation reader.
The magnet may be located inside the wireless communication device or may be located proximate to the wireless communication device and attached to the wireless communication device.
One embodiment locates the magnet inside a chamber comprised of two core pieces coming together around a housing having a magnet and forming two gaps at opposite ends. The magnet is free to rotate inside the chamber. In one orientation, the magnet is substantially perpendicular to the magnetic surface portion of an article and emanates magnetic flux into the core pieces, providing them with a sufficient magnetic force to cause an attraction between the wireless communication device and the magnetic surface portion. Detachment is accomplished by rotating the magnet to a position that is substantially parallel to the magnetic surface portion, thereby causing the magnetic flux to be emanated in the gaps and sufficiently reducing the magnetic force in the core pieces so as to detach the wireless communication device.
In another embodiment, the wireless communication device is located inside the core pieces and is either located near the gap or away from the gap. If located near the gap, the presence of magnetic flux indicates that the wireless communication device is not attached to a magnetic surface portion of an article. If located away from the gap, the presence of magnetic flux indicates that the wireless communication device may be attached to a magnetic surface portion. In another embodiment, two separate wireless communication devices may be located in each core piece so that one can be located near the gap and the other away from the gap. In this manner, only one wireless communication device should sense magnetic flux at a given time and the sensing of magnetic flux by one of the wireless communication devices. The status of whether or not the wireless communication device is attached or detached from a magnetic surface portion may be communicated wirelessly.
The housing having a magnet may be rotated in a number of manners. One embodiment uses a spring and latch combination. A latch is placed in a notch in the housing that maintains the housing and the magnet in an orientation that keeps the wireless communication device attached to the magnetic surface portion of an article. When the latch is released, the energy stored in the spring causes the housing to rotate the magnet in an orientation so as to detach the wireless communication device from the magnetic surface portion.
In a different embodiment, a mechanical resonator, or other device that responds to particular resonant frequency, is used to rotate the magnet to detach the wireless communication device from the magnetic surface portion of an article. An external device may be used to generate the resonate frequency or the control system of the wireless communication device may be adapted to generate such frequency upon receipt of a communication command. The wireless communication device contains a frequency generator that may also generate the resonant frequency to detach the wireless communication device from the magnetic surface portion. This can occur if the control system receives a command to detach.
In another embodiment, the wireless communication device may contain a piezoelectric device that is powered from the power source by the control system to generate a mechanical force to release the latch, thereby detaching the wireless communication device from the magnetic surface portion.
In another embodiment, the chamber has an open portion for an external device to be inserted inside said chamber proximate to the magnet. The magnet is oriented such that its magnetic flux extends out to the magnetic surface portion, creating an attraction between it and the wireless communication device. The insertion of such a magnetic shorting material causes the magnet to reverse polarity, thereby causing the magnetic flux to extend in a direction substantially parallel to the magnetic surface portion such that an attraction sufficient to keep the wireless communication device attached to the magnetic surface portion is not longer present.
In another embodiment, the magnet is located in a chamber and does not rotate. The magnet can move in a direction perpendicular to the magnetic surface portion, but does not change its polarity. In an attached state, the magnet is located on the side of the chamber nearest the magnetic surface portion such that its magnetic flux emanates into the magnetic surface portion to create the attraction. To detach the wireless communication device, an external device having magnetic properties is brought into proximity to the chamber to attract the magnet to the opposite end of the chamber that is farthest from the magnetic surface portion. This causes the magnet""s magnetic flux to move further from the magnetic surface portion such that the amount of flux emanating into the magnetic surface portion is no longer sufficient to create an attraction that is strong enough to keep the wireless communication device attached to the magnetic surface portion of the article.
In another embodiment, the wireless communication device contains conductive tabs that form an antenna. The antenna is a slot antenna if the tabs are attached across a slot in a magnetic surface portion of an article. The antenna is a pole antenna if the tabs are not attached across such a slot. In one embodiment, the tabs are permanent magnets that emanates magnetic flux to attract the wireless communication device to the magnetic surface portion of the article that is also magnetic. To detach, either an external device or an electromagnet inside the wireless communication device alters the magnetic flux.
In another embodiment, the wireless communication device alters the magnetic force to detach the wireless communication device from the magnetic surface portion by generating a magnetic force sufficient to alter or cancel the magnetic force created by the magnet. The wireless communication device may contain a core with a coil wound around if such that the control system can place a voltage across the coil, using power from the power source to create an electromagnet having a magnetic force sufficient to alter the magnetic force created by the magnet associated with the wireless communication device so as to detach the wireless communication device.
In another embodiment, the wireless communication device contains an electromagnet for use as the magnetic force to attach the wireless communication device to the magnetic surface portion of an article. One embodiment has an electromagnet that is created by a core with a coil wound around it. The control system places a voltage across the coil using power from the power source to create an electromagnet having a magnetic force sufficient to attract the wireless communication device to the magnetic surface portion. To detach the wireless communication device from the magnetic surface portion, the control system disables power from the core so that the core is no longer an electromagnet.
In another embodiment, tabs connected to the wireless communication device form electromagnets. The tabs are core material with a coil would around them. The wireless communication device runs a current through the coil to cause the tabs to function as be an electromagnet and, thus, attach the wireless communication device by magnetic force to a magnetic surface portion of an article. To detach itself from the magnetic surface portion, the wireless communication device disconnects the current to the coils.
The wireless communication device may use, as part of its force to attach to a magnetic surface portion, a non-magnetic force in addition to a magnetic force. When the magnetic force is altered, the non-magnetic force is insufficient alone to keep the wireless communication device attached to the magnetic surface portion.